Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$174.75	9.385%	$191.1503	$191.15	$191.15	$191.20
Purchase #2	$160.90	3.803%	$167.019	$167.02	$167.00	$167.00
Purchase #3	$59.57	5.601%	$62.9065	$62.91	$62.90	$62.90
Purchase #4	$97.71	5.657%	$103.2375	$103.24	$103.25	$103.20
Purchase #5	$114.88	13.446%	$130.3268	$130.33	$130.35	$130.30
Purchase #6	$28.28	5.645%	$29.8764	$29.88	$29.90	$29.90
Purchase #7	$217.41	12.224%	$243.9862	$243.99	$244.00	$244.00
7 purchase totals =	$853.50		$928.5027	$928.52	$928.55	$928.50